<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>

    *{
      margin: 0;
      padding: 0;
    }

    .container{
      width: 600px;
      margin: 100px auto;
      /* display: flex; */
      background: rgb(8, 20, 12);
      /* justify-content: center;
      align-items: center; */
    }

    .header,
    .footer{
      width: 600px;
      height: 100px;
      background: #444;
      font-size: 16px;
      color: #fff;
      display: flex;
      justify-content: center;
      align-items: center;
    }

    .section{
      width: 600px;
      height: 400px;
      display: flex;
    }
    

    .section .left{
      width: 100px;
      display: flex;
      font-size: 16px;
      color: #fff;
      justify-content: center;
      align-items: center;
      background: rgb(163, 187, 171);
    }

    .section .right{
      width: 100px;
      display: flex;
      font-size: 16px;
      color: #fff;
      justify-content: center;
      align-items: center;
      background: rgb(199, 144, 144);
    }

    .section .content{
      display: flex;
      flex: 1;
      background: rgb(206, 231, 214);
    }
  </style>
</head>
<body>
  <div class="container">
    <header class="header">header</header>
    <section class="section">
    <aside class="left">left</aside>
    <section class="content"></section>
    <aside class="right">right</aside>
    </section>
    <section class="footer">footer</section>
  </div>
</body>
</html>